MOSCOW, April 18. /TASS/. Air defense units in the Moscow Region were put on alert as part of a snap combat readiness check, the Russian Defense Ministry reported on Tuesday.

"Units of air defense missile and radio-technical forces made a march to their deployment positions and were put on combat alert," a spokesman for the ministry said. "During the redeployment, the personnel practiced thwarting sabotage and reconnaissance groups."

The check is being held after the winter training period and involves over 1,000 personnel and more than 100 weapon systems and equipment.

A spokesperson for the ministry also said "that the check involves S-400 Triumf and S-300 Favorit anti-aircraft missile systems, Pantsyr-S missile/gun launchers, as well as radars of various ranges."

Various mobile jamming platforms are used during the ongoing check to simulate battlefield conditions, the ministry added.

The S-400 Triumf is the most advanced long-range anti-aircraft missile system that went into service in 2007. It is designed to destroy aircraft, cruise and ballistic missiles, including medium-range missiles, and can also be used against ground objectives.

The S-400 can engage targets at a distance of 400 km and at an altitude of up to 30 km.